Apparatus for forming seal and reinforced holes through the end of a flexible resin impregnable tubular pipeliner

ABSTRACT

A method and apparatus for forming sealed and reinforced holes through the end of a flexible, resin-impregnable, tubular pipe liner for securing a cable thereto and for sealing the end of the liner. The liner is installed into an existing conduit either by pulling a cable secured to holes at the front end of the liner or by eversion of the liner while securing a hold-back cable to holes at the trailing end of the everting liner. Holes are cut through the liner, and resin is impregnated into the region about each hole and hardened to form an integral grommet or reinforcement. A mold for impregnating the region about the hole includes a lower mold body with a projecting spigot and a groove thereabout. An upper mold body has a central opening with a groove thereabout, the upper mold body fitting over the spigot. A tube fits into the central opening and receives a resin, which is then forced by a plunger down the tube and allowed to harden and form a secure and reinforced hole for attaching a pull-in or hold-back rope or cable.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional of application Ser. No. 08/497,147, filed Jun. 30,1995, now U.S. Pat. No. 5,919,327 issued on Jul. 9, 1999.

BACKGROUND OF THE INVENTION

The present invention relates generally to a method and apparatus forthe installation of a cured in place liner within the interior of aconduit or pipeline, such as a sewer pipe, and, more particularly, to amethod and apparatus for sealing the end of the liner and for securing acable to the liner for installation.

It is generally well known that conduits or pipelines, particularlyunderground pipes, such as sanitary sewer pipes, storm sewer pipes,water lines and gas lines, that are employed for conducting fluidsfrequently require repair due to fluid leakage. The leakage may beinward, from the environment into the interior or conducting part of thepipe, or outward, from the conducting part of the pipe into thesurrounding environment. Leakage of this type may be due to improperinitial installation of the pipe, deterioration of the pipe itself dueto normal aging or to the effects of conveying corrosive or abrasivematerials, cracking of the pipe or of pipe joints due to environmentalconditions such as earthquakes, the movement of large vehicles orsimilar natural or man made vibrations, or any other such causes.Regardless of the cause, such leakage is undesirable and may result inwaste of the fluid being conveyed by the pipe, in damage to thesurrounding environment and in the possible creation of dangerous publichealth hazards.

Because of ever increasing labor and machinery costs, it is becomingincreasingly more difficult and less economical to dig up and replaceunderground pipes, or portions or sections of such underground pipes,that may be leaking. As a result, various methods have been devised forthe in situ repair or rehabilitation of the existing pipes, therebyavoiding the expenses and hazards associated with digging up andreplacing the pipes or pipe sections. One of the more successful piperepair or rehabilitation processes that is currently used is called theInsituform® Process and is described in U.S. Pat. Nos. 4,009,063;4,064,211; and 4,135,958, the contents of all of which are incorporatedby reference herein.

Briefly, in the Insituform Process, an elongated flexible tubular linerof a felt fabric, foam or similar resin impregnable material that hasbeen impregnated with a thermosetting synthetic catalyzed resin isinstalled within the existing pipe. The impregnated liner may be pulledinto the conduit by a rope or cable, and a fluid impermeable inflationbladder or tube is then everted within the liner. Generally, however,the liner is installed utilizing an inverting (or everting) process, asdescribed in the latter two patents.

The flexible tubular liners have a smooth layer of relatively flexible,substantially impermeable material coating the outside of the liner inits initial state, which impermeable layer ends up on the inside of theliner after the liner is inverted. As the flexible liner is installed inplace within the pipe, the liner is pressurized from within, preferablyutilizing a fluid such as water, forcing the liner radially outwardly toengage and conform to the interior surface of the pipe. The resin isthen cured to form a relatively hard, tight fitting, rigid pipe liningthat effectively seals any cracks and that repairs any pipe or pipejoint deterioration in order to prevent further leakage either into orout of the pipe. The cured resin liner also serves to strengthen theexisting pipe walls so as to provide added structural support for thesurrounding overburden.

All of these existing liner insertion methods, especially for theinstallation of a liner into a large diameter pipe, require positivecontrol of the insertion and inversion of the liner throughout theentire inversion process.

The known methods for providing the pressure necessary to invert theliner within the pipe and to push it along the length of the pipe mustalso involve means for controlling the feed rate of the liner, i.e., therate at which the liner is inverted and pushed into the pipe. Generally,in the Insituform Process, the resin-impregnated liner, which istypically stored in layers, is placed at a manhole adjacent the conduitto be lined, and the leading end of the liner is sealingly clamped tothe proximal inside end of an eversion tube in order to create a fluidseal. The pressurized fluid, such as water, then forces the liner toinvert into the conduit. Various means have been provided forcontrolling the rate at which the liner inverts and is fed into theconduit. The typical means within the Insituform Process for controllingthe "feed rate" of the liner is by restraining the trailing end of theresin-impregnated liner as it is everted into the conduit using a cableor a hold-back rope. By restraining the trailing uneverted end of theliner, the liner does not evert too quickly, thereby ensuring that thepressure is maintained within the liner.

In addition to being restrained, the trailing end of the liner must alsobe sealed so that, when the tube is fully everted, the pressurized wateror other fluid within the pipe is contained. At times, these pressurescan be large. For example, the hold-back force needed during eversion ofa 60-inch diameter liner tube with a 30-foot head of water is in excessof 20,000 pounds. When the tube is fully everted, the end of the linermust resist double that force.

Various means have been proposed to secure a holdback rope or cable tothe trailing end of the liner for restraining the trailing end of theliner and for distributing the pulling stress over the entire width ofthe end of the liner. It has been proposed to seal the liner at thepoint of attachment of the hold-back cable in order to prevent waterfrom escaping through the uneverted end of the liner and penetratinginto the resin-wet material of the uneverted and everted portions of theliner ahead. One such cable end seal is shown in U.S. Pat. No.4,776,370, the contents of which are incorporated herein by reference.

In the process described in U.S. Pat. No. 4,776,370, a short length ofcured synthetic resin film, such as "Tuftane", is bonded directly to theoutside of the flattened trailing end of the liner to seal the end ofthe liner. A series of holes is then formed through the flattened end ofthe liner. Special plates or straps also having holes are spaced outalong both sides of the flattened end of the liner such that those holesalign with the holes through the liner. Fastening elements such as nutsand bolts are placed through the holes of both the plates and the linerin order to secure the plates to the liner and seal the end of theliner. The hold-back cable is then attached, either directly or by wayof an additional connector, to the plates for regulating the feed rateof the liner.

Another prior art way of securing a cable or rope to the trailing end ofthe liner for sealing the end of the liner and for distributing thepulling stress over the entire width of the flattened liner end is touse a series of holes as shown in FIG. 1. In this method a liner 2having a trailing end 4 is flattened, and a series of holes 11 is formedthrough liner 2. Metal grommets may optionally be placed in holes 11 asreinforcement. A cable or rope 10 is then woven through holes 11 acrossliner end 4, and a number of rope handles 12 are looped around cable 10at the region where cable 10 passes through liner end 4. Handles 12 arethen tied to a hold-back cable for restraining trailing end 4 of liner 2and for controlling the rate of eversion. In both of these conventionalmethods, the points at which the holes are formed through the liner andat which the handles emerge from the end of the liner must all be sealedin order to prevent water or fluid leakage. The assembly of such sealedends is time consuming, difficult and expensive, and the seals arerarely totally effective.

Accordingly, it is desirable to provide a method and apparatus forforming attachment points or holes for the holdback cable, such thatthese holes are fully sealed and distribute the pulling forceseffectively across the width of the felt or the resin-absorbent materialand such that the resulting seals withstand the pressure built up whenthe liner is completely inverted.

SUMMARY OF THE INVENTION

Generally speaking, in accordance with the invention, a method andapparatus are provided for forming sealed and reinforced holes throughthe end of a flexible resin impregnable tubular pipe liner for securinga cable thereto and for sealing the end of the liner. The liner is to beinstalled into an existing conduit either by pulling the liner into theconduit using a cable secured to holes at the front end of the liner orby eversion of the liner while securing a hold-back cable to holes atthe trailing end of the everting liner. First, the holes are cut throughthe liner, and then resin is impregnated into the region about each holeand hardened to form an integral grommet or reinforcement about thehole. A mold for impregnating the region about the hole includes a lowermold body with a projecting spigot and a groove thereabout. An uppermold body has a central opening with a groove thereabout, the upper moldbody fitting over the spigot but leaving room to engage a tubetherebetween. A tube fits into the central opening and receives a resinwithin it. The resin is forced by a plunger down the tube, about thespigot and into the region surrounding the hole in the liner. Afterinjection, the resin is allowed to harden, thereby forming a secure andreinforced hole for attaching a pull-in or hold-back rope or cable.

The liner can be folded at the end, and reinforcing disks can be placedon the outsides of the folded liner in order to distribute the pullingforces along the material. Also, a capstan can be attached to theintegrally-formed grommets between the two folded sides of the liner endportion in order to allow the hold-back cable to be wrapped around it sothat, when one end of the cable is fixed, the other end of the cable canbe slackened to allow the liner to evert slowly within a conduit.

Accordingly, it is an object of the invention to provide an improvedmethod for securing a hold-back, or restraining, cable to a flexibleresin impregnable tubular pipe liner that is to be installed within anexisting conduit.

It is another object of the invention to provide an improvedintegrally-formed grommet in a resin impregnable liner.

It is a further object of the invention to provide an improved seal forthe end of a flexible resin impregnable liner that is to be installedwithin an existing conduit.

It is yet another object of the invention to provide an improvedreinforced hole in a flexible resin impregnable liner for mountingreinforcement disks for sealing the end of the liner that is to beinstalled in an existing conduit.

It is yet a further object of the invention to provide an apparatus forforming an integral grommet about a hole in a flexible resin impregnabletubular liner.

It is still a another object of the invention to provide a method forforming an integral reinforced grommet in a hole in a flexible resinimpregnable liner.

It is still a further object of the invention to provide an apparatusand method for sealing the end of a flexible resin impregnable linerthat is to be installed within an existing conduit.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

The invention accordingly comprises the several steps and the relationof one or more of such steps with respect to each of the others, theapparatus embodying features of construction, combinations andarrangement of parts which are adapted to effect such steps, and thearticle which possesses the characteristics, properties and relation ofelements, all as exemplified in the detailed disclosure hereinafter setforth, and the scope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference is had to thefollowing description taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a perspective view of a prior art method for securing ahold-back or restraining cable to the trailing end of an evertingcured-in-place liner;

FIG. 2 is a perspective view of the trailing end of a flattened resinimpregnable liner with several holes formed in accordance with aninitial step in the invention;

FIG. 3 is an exploded perspective view of a mold arrangement forintegrally forming grommets in the resin impregnable liner in accordancewith the invention;

FIG. 4 is a sectional view of the mold arrangement of this inventionpositioned through a hole formed in an end of a resin impregnable liner;

FIG. 5 is a perspective view of the flattened end of the liner of FIG. 4with a welded-film end seal;

FIG. 6 is a perspective view showing the use of the integrally-formedgrommet for securing a hold-back cable to the trailing end of the liner;

FIG. 7 is a cross-sectional view of the end of a fully everted resinimpregnated liner showing the sealed end in accordance with theinvention;

FIG. 8 is a cross-sectional view of the sealed end of a liner withreinforcing disks in place;

FIG. 9 is a cross-sectional elevational view showing a cured-in-placeliner being everted into an underground conduit using a capstan, asdescribed in an embodiment of the invention; and

FIG. 10 is a perspective view showing the use of a capstan and theintegrally-formed grommet for securing a holdback cable to the trailingend of the liner.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 2 depicts a tubular liner 21 having a trailing end 22 and formedfrom several layers of felt 23. An outermost flat layer 24 has aflexible impermeable coating 26 on the outside thereof. As shown in FIG.2, liner 21 is collapsed, and end portion 22 is flattened. One or moreholes 27 are drilled through all the layers of felt 23 and coating 26with a suitable hole saw. The number of holes 27 that are formed dependsupon the diameter of liner 21. For a liner with a diameter of less thanten inches, one hole is sufficient. For a liners with a very largediameter, i.e., sixty inches or more, there may be a need for eight ormore holes.

FIG. 3 depicts a mold arrangement 31 in which a lower half 32 and a tophalf 33 are arranged inside a clamping means 34. The mold halves areconveniently circular, but it will be understood that other shapes maybe used. The mold halves are made of a suitable material, such aspolypropylene, that will not stick to the thermosetting resin or othertype of resin that is to be cast within the mold. Lower half 32 of mold31 has a central spigot 36 that is frusto-conical in shape with a slighttaper towards the top to ease its removal from the cast insert ofthermosetting resin. Spigot 36 cooperates with a central hole 37 formedin top half 33 of mold 31, through which hole resin may be introduced.

A filler tube 38 is provided to mate with hole 37 in top half 33 of mold31 and form a sliding fit with a plunger 39. Conveniently, filler tube38 and plunger 39 are also made of polypropylene or other material thatwill not stick to the resin. As shown in FIGS. 3 and 4, the uppersurface of lower half 32 is formed with an annular groove 35a aboutspigot 36. Similarly, top half 33 is formed with an opposing annulargroove 35b that, together with groove 35a, forms a pocket or mold toallow resin be injected into the region about the hole and cure into aself-forming seal or grommet in accordance with the invention.

FIG. 4 shows a sectional view of mold 31 positioned through hole 27 cutthrough felt layers 23 of liner 21. When mold 31 is positioned in hole27, bottom half 32 of mold 31 is placed under liner 23 such that centralspigot 36 is placed through hole 27. Top half 33 of mold 31 is thenplaced on the opposite side of liner 23 so that central hole 37cooperates matingly with spigot 36. Top and bottom halves 33, 32 of mold31 are then clamped together using clamping means 34 such that theportions of felt layers 23 and coating 26 immediately adjacent to hole27 are trapped within the pocket formed between opposing annular grooves35a, 35b and are held there by the opposing outer edges of top andbottom halves 33, 32 of mold 31.

The integrally-formed grommets or reinforced holes in liner 21 areformed by mixing a liquid resin and hardener, which mixture is designedto harden at room temperature within a reasonably short time aftermixing. The resin system may be any commercially available liquid resinsystems, such as unsaturated polyester, epoxy or polyurethane. After theresin has been mixed, a measured quantity 30 is poured into filler tube38 and is then forced into the pocket formed between opposing grooves35a, 35b and into felt 23 trapped therein by pushing plunger 39 downinto tube 38. It has been found that this displaces air in felt 23 bymoving the air radially from the center edges of hole 27. When the resinis hard, mold 31 is removed, leaving the felt layers locked together andsealed to the impermeable coating 26 with an integrally-formed grommet40. By using several molds at the same time, all the holes 27 can be sosealed and reinforced with integrally-formed grommets more or lesssimultaneously. Alternatively, one mold may also be used to sequentiallyseal and reinforce each hole 27 in turn by integrally forming a grommetwithin each one.

After integrally-formed grommets 40 have been provided in all the holes27, end 22 of flattened liner 21 is provided with a seal by welding afilm 41 around the end of liner 21, as shown in FIG. 5, in which thewelds are shown by cross-hatching 42. The film is made of the samematerial as the impermeable coating. The weld 42 may be accomplished byheat or solvent welding, depending on the particular coating material.It is found convenient to seal the edge of the film leaving an extensionflap 43 for injecting into liner 21 the resin with which the felt is tobe impregnated.

Liner 21 is then fully impregnated with resin and is then ready to beinserted into the conduit that is to be lined. The liner may optionallybe impregnated with resin after transport to the job site. A rope and alayflat hose are then attached to the end of liner 21 to control therate of eversion and to transport the layflat hose to the far end of thepipeline so that hot water may be pumped to the end in order to effecthardening of the resin throughout the pipeline. FIG. 6 shows anarrangement wherein a rope 61 is passed through integrally-formedgrommets 40 in end 22 of liner 21. This arrangement is satisfactory fora liner with a smaller diameter because the molded holes will distributethe load on the holdback rope 61 into the felt layers during eversionand will be strong enough to hold the end of the liner closed when theeversion is complete, as shown in sectional view in FIG. 7.

For a liner of larger diameter, however, the force applied to holes 27and integrally-formed grommets 40 may be so great as to split the resinand felt molding at position 51, shown in FIG. 7. For such liners, showntriple-folded in FIG. 8, a metal reinforcing disk 52 may be secured onthe outside of the liner by a bolt 53 passing through integrally-formedgrommets 40. Each disk 52 has a diameter that is appreciably greaterthan the diameter of grommets 40 so that the loads imposed by the feltresisting the water pressure are taken in the plane of reinforcing disks52 rather than at right angles to the disks, as shown by arrows 55 and56 in FIG. 7. When such reinforcing disks 52 are used, one or both areequipped with a suitable attachment point 57 to which the hold-back ropemay be tied.

The use of hold-back rope 61 with the integrally-formed grommets 40 ofthis invention can sometimes lead to a situation in which, if the liningtube must follow a somewhat curved path due to the conduit being otherthan straight, holdback rope 61 comes to bear against the evertedresin-impregnated liner portion and against the impermeable layer on theinside of the everted liner. Due to the tension in holdback rope 61, themotion of rope 61 as it is being slowly released may create frictionbetween the rope and the liner, causing the liner to rub or burn away,resulting in an undesirable hole within the lining. This situation canbe ameliorated, as shown in FIGS. 9 and 10, by attaching a capstan or apulley 71 to the trailing end 21 of the liner so as to define tworeaches 73,74 of hold-back rope 61 extending from the capstan 71 to alocation when the ends of the rope can be held. When one of thehold-back rope reaches 73 is fixed, the other reach 74 is slackened andis allowed to be fed and slide around the capstan 71 as the eversionproceeds. Thus, the fixed reach 73 will carry the higher tension andwill perform the main hold-back function but does not move relative tothe liner already everted. The second reach 74, which is fed, will carrymuch less tension and controls the rate of eversion. In thisarrangement, only the second reach 74 will be allowed to move relativeto the inner surface of the liner, and friction is reduced.

Because the difference in tension between the two reaches 73,74 ofhold-back rope 61 depends upon a number of factors, including thecoefficient of friction of the capstan 71 surface, the angle of wrap ofthe hold-back rope 61 around the capstan 71 and the number of wraps ofthe hold-back rope 61 around the capstan 71. Thus, the hold-back rope 61may wrap around the capstan for only part of a time but shouldpreferably wrap around the capstan 71 at least once in order to increasethe frictional sliding resistance between the rope 61 and the capstan71.

As shown in FIG. 10, the capstan 71 should preferably be placed betweenthe two sides 76,77 of the flattened and folded liner end portion 21 sothat pulling forces from the hold-back rope are evenly distributedbetween the two sides 76,77 of the flattened and folded liner endportion 21. In addition, metal reinforcing disks 52 may be secured onthe outside of the liner, using the same bolt that passes through theintegrally-formed grommets 40 and holds the capstan 71, to furtherdistribute the pulling forces.

It will be appreciated that the size and number of reinforcing disks 52or integrally-formed grommets 40 will be selected for the thickness anddiameter of the felt liner being used and for the number of holes 27formed therein. Typically, the resin reinforcement of theintegrally-formed grommets 40 will have an outer diameter in the rangeof three to six inches, and the holes 27 themselves will have an innerdiameter in the range of 0.75 inches to 1.5 inches. As described above,the holes 27 are formed by spigot 36 of mold 31 but could equally beformed by drilling after molding. In the description above, theintegrally-formed grommets 40 are formed from a liquid resin thathardens by a chemical reaction, but it will be appreciated that theycould be formed by injection of a molten plastic which hardens as itcools.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained and,since certain changes may be made in carrying out the above process, inthe described product, and in the constructions set forth withoutdeparting from the spirit and scope of the invention, it is intendedthat all matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

What is claimed is:
 1. A method of installing a flexible resinimpregnable tubular liner having a fluid impermeable outer coating on aresin impregnable material into an existing conduit,comprising:flattening one end of the liner; forming at least one openingthrough the flattened liner; impregnating a resin into the region of theresin impregnable material about the at least one opening; hardening theresin to bond the layers of the resin impregnable material of theflattened liner together; attaching a securing member to the linerthrough the hardened resin; impregnating the tubular liner; insertingthe liner into an existing conduit; and curing the liner in place. 2.The method of claim 1, wherein the liner is inserted by pulling into theexisting conduit.
 3. The method of claim 1, wherein the liner isinserted by everting into the existing conduit.
 4. The method of claim1, wherein said step of attaching a securing member comprises tying arestraining means directly through said at least one opening and throughsaid hardened resin for slowing said step of inserting the liner.
 5. Themethod of claim 4, wherein said restraining means comprises a hold-backcable.
 6. The method of claim 1, wherein said step of attaching asecuring member further comprises the step of:attaching a capstanthrough said at least one opening and through said hardened resin; andsecuring a restraining means directly to said capstan for slowing saidstep of inserting the liner.
 7. The method of claim 6, wherein said stepof securing a restraining means comprises tying a hold-back cable tosaid capstan.
 8. The method of claim 6, wherein said step of securing arestraining means comprises wrapping a hold-back cable around saidcapstan, whereby a first end of said holdback cable restrains insertionof the liner and a second end of said hold-back cable provides slack forpermitting said insertion to proceed.